Trump trade advisor Peter Navarro apologized on Tuesday for saying there was a "special place in hell" for Canadian Prime Minister Justin Trudeau.

"That was my mistake. Those were my words," Navarro said at a Washington conference hosted by The Wall Street Journal.

"My job, my mission, was to send a very strong signal of strength. And this was particularly important on the eve of an even more, a far more important summit on Korea. And the problem was, in conveying that message, I used language that was inappropriate," Navarro said.

Navarro made his earlier comments on Sunday, after the G-7 summit, in which President Donald Trump struck a tough position on trade with the United States' closest allies. The president withdrew American support for a joint communique signed by the other G-7 countries, including Canada.

"There's a special place in hell for any foreign leader that engages in bad faith diplomacy with President Donald J. Trump and then tries to stab him in the back on the way out the door," Navarro told "Fox News Sunday."

Trump had cited comments Trudeau made at a news conference held after Trump had left for the North Korean nuclear summit in Singapore. Trudeau called American tariffs on Canadian steel and aluminum "unjustly applied to us" and "kind of insulting."

"Canadians are polite, we're reasonable, but we also will not be pushed around," Trudeau said.

"[Trudeau] had a news conference, that he had because he assumed I was in an airplane and I wasn't watching," the president said at a press briefing. "He learned. That's going to cost a lot of money for the people of Canada. He learned. You can't do that. You can't do that."

The White House did not immediately respond to a request for comment from CNBC.

Here is Navarro's full apology:

"The day before, on Saturday, at the end of what was a very successful and friendly G-7 summit, shortly after Air Force One and the president left Canadian airspace, the prime minister of Canada held a press conference that this administration viewed as a breach of protocol and inappropriate. The next morning, on Fox News, my job, my mission, was to send a very strong signal of strength. And this was particularly important on the eve of an even more, a far more important summit on Korea. And the problem was in conveying that message I used language that was inappropriate. I basically lost the power of that message. I own that. That was my mistake. Those were my words. And if I can quote the words of the great [football coach] "Bear" Bryant, 'When you make a mistake, you should admit it, learn from it, don't repeat it.'"